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Image capture lens and image capture apparatus

a technology of image capture and lens, which is applied in the field of image capture lenses and image capture apparatuses, can solve the problems of increasing the total length of the lens, difficult to obtain a sufficient angle of view, and the method is not well suited for miniaturization and weight saving, so as to improve compactness and portability, simplify the barrel structure, and shorten the focal length

Inactive Publication Date: 2009-09-10
SONY CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention proposes an image capture lens with a simplified barrel structure that reduces the displacement of the first lens group and shortens the total length of the lens while maintaining excellent optical performance. The lens includes a negative first lens and a negative or positive cemented lens, and the movement of the first lens group is controlled by cams. The lens has a short focus and a compact size, making it ideal for miniaturization and portability. The image capture lens satisfies conditional expressions to control the displacement of the first lens group and the ratio between the radius of curvature of the image surface and the radius of curvature of the second lens group. The image capture apparatus includes the image capture lens and an imaging device.

Problems solved by technology

Although the macro lenses disclosed in the above-described Japanese Unexamined Patent Application Publication Nos. 62-195617 and 63-247713 employ a floating method, there is a problem in that if the amount of movement of a lens group becomes large, the total length of the lenses increases.
There has been a problem in that it is difficult to obtain a sufficient angle of view as a result.
Accordingly, there has been a problem in that the structure thereof becomes complicated, and thus the method is not well suited for miniaturization and weight saving.

Method used

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  • Image capture lens and image capture apparatus
  • Image capture lens and image capture apparatus
  • Image capture lens and image capture apparatus

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

1. First Embodiment

[0037]In FIG. 1, reference numeral 1 denotes a retrofocus image capture lens (macro lens) according to a first embodiment as a whole. The image capture lens includes, in order from an object side, a first lens group GR1, which is movable along an optical axis and has positive refractive power, and a fixed second lens group GR2 having negative refractive power.

[0038]In the image capture lens 1, focusing is performed by moving the first lens group GR1 along the optical axis. When focusing is changed from infinity focusing to close-up focusing, the first lens group GR1 having positive refractive power is moved from an image surface side to the object side.

[0039]That is to say, the image capture lens 1 employs an asymmetric (retrofocus) lens system in which the first lens group GR1, which is near to the object side, is moved along the optical axis, whereas the second lens group GR2, which is near to the image side, is fixed. Thereby, it is possible to make the back fo...

second embodiment

2. Second Embodiment

[0052]In FIG. 4, reference numeral 2 denotes a retrofocus image capture lens (macro lens) according to a second embodiment as a whole. The image capture lens includes, in order from an object side, a first lens group GR1, which is movable along an optical axis and has positive refractive power, and a fixed second lens group GR2 having negative refractive power.

[0053]In the image capture lens 2, focusing is performed by moving the first lens group GR1 along the optical axis. When focusing is changed from infinity focusing to close-up focusing, the first lens group GR1 having positive refractive power is moved from an image surface side to the object side.

[0054]That is to say, the image capture lens 2 employs an asymmetric (retrofocus) lens system in which the first lens group GR1, which is near to the object side, is moved along the optical axis, whereas the second lens group GR2, which is near to the image side, is fixed. Thereby, it is possible to make the back ...

third embodiment

3. Third Embodiment

[0066]In FIG. 7, reference numeral 3 denotes a retrofocus image capture lens (macro lens) according to a third embodiment as a whole. The image capture lens 3 includes, in order from an object side, a first lens group GR1, which is movable along an optical axis and has positive refractive power, and a fixed second lens group GR2 having negative refractive power.

[0067]In the image capture lens 3, focusing is performed by moving the first lens group GR1 along the optical axis. When focusing is changed from infinity focusing to close-up focusing, the first lens group GR1 having positive refractive power is moved from an image surface side to the object side.

[0068]That is to say, the image capture lens 3 employs an asymmetric (retrofocus) lens system in which the first lens group GR1, which is near to the object side, is moved along the optical axis, whereas the second lens group GR2, which is near to the image side, is fixed. Thereby, it is possible to make the back ...

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Abstract

An image capture lens includes: when changed from infinity to close focusing, a first lens group moving from an image to an object with positive refractive power; and a second lens group fixed relatively to the image with negative refractive power, wherein the first lens group includes a negative first lens having a strong concave surface facing the image, the second lens group includes one negative lens having a strong concave surface facing the image or a negative cemented lens including positive and negative lenses, and conditional expressions; 0.7<f1 / fi<0.9, 1.0<bf / fi<1.4, 0.5<Rf2 / Rr2<1 are satisfied where fi: overall focal length, f1: first-lens-group focal length, bf: overall back focus, Rf2: radius of curvature of the image-side surface of the lens nearest to the object, and Rr2: radius of curvature of the surface nearest to the image of the second lens group.

Description

CROSS REFERENCES TO RELATED APPLICATIONS[0001]The present invention contains subject matter related to Japanese Patent Application JP 2008-055178 filed in the Japanese Patent Office on Mar. 5, 2008, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to image capture lenses and image capture apparatuses. For example, the present is suitably applied to a macro lens which is used for an interchangeable-lens camera and a digital still camera.[0004]2. Description of the Related Art[0005]To date, a macro lens has been a versatile lens capable of close-up shooting at an extremely close position to a subject, and at the same time, capable of shooting at infinity in the same manner as a normal lens. In general, it is desirable for the macro lens to have been subjected to favorable aberration correction both for closest-up focusing and for infinity focusing.[0006]In order to meet this ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B9/04
CPCG02B7/08G02B13/26G02B13/04G02B9/04
Inventor SUEYOSHI, MASAFUMI
Owner SONY CORP